Bureaucrats and Experts

What's the difference between a bureaucrat and an expert?  Here's a NYTimes science essay in which a doctor compares his relationship with plumbers over a puzzling problem with his dishwasher to the relationship between patients who have their own theories of their illnesses and a doctor.  He ends:

When matters of personal health (or home appliances) are at stake, we want a lot more than expertise from our experts. The rational world suddenly loses its appeal; dull, steady scientific observation seems only dull and steady. We want some pixie dust, a little magic, an eccentric genius who can see through the usual mumbo-jumbo to the core of the problem (paging Dr. House).
But until our prince comes, we are left with the most basic, bare-bones determination: do we trust this guy or not? And this decision, rather than following along a perfectly manicured line of reasoning and evidence, relies on that least scientific of all human inclinations — the simple leap of faith.

 So what distinguishes a bureaucrat dealing with the public from a plumber dealing with a homeowner or a doctor dealing with a patient? I suspect in some cases, perhaps many, an FSA technician at the desk in a county office is seen as an "expert" by the farmer she's serving, rather than being viewed as a "bureaucrat".  One thing which strikes me is: in the doctor/patient, plumber/homeowner scenarios both parties share the same goal, curing the illness or fixing the appliance.  When the relationship is viewed as bureaucrat and customer/client there's little or no assumption of a shared goal.